Wi-Fi has become a very important feature in modern electronic devices, including smart phones, tablets, wearable devices, Internet of Things (IOT) devices, notebooks, PCs, etc. Wi-Fi can provide the cheaper and faster internet experience than others. But for the long coverage and high throughput, Wi-Fi consumes more power. For longer battery life, many low power mechanisms are provided for different user scenarios.
To save power consumption, communication devices (e.g. Wi-Fi stations) generally keep in low power mode (e.g. Wi-Fi power saving mode (PSM)), and have to wake up to receive beacon for every 102.4 ms (i.e. beacon interval) by a target beacon transmission time (TBTT) timer, so that Wi-Fi stations (STAs) will not miss data sent from the access point (AP). In addition, a delivery traffic indication map (DTIM) bit is set by the AP in the beacon to notify a specific Wi-Fi STA of buffered data. Therefore, the Wi-Fi device turns the radio frequency (RF) antenna on for receiving buffered data from the AP when the DTIM bit of the beacon is set to “1”, whereas the Wi-Fi device/STA does not turn the RF antenna on when the DTIM bit is set to “0”.
Refer to FIG. 1, which is a schematic diagram of current consumption of a Wi-Fi station in power saving mode according to the prior art. In FIG. 1, the Wi-Fi station in sleep period “A” does not perform beacon reception, consuming less current, and in wake-up period “F” performs beacon reception, which has the highest power consumption during the power saving mode. As shown in FIG. 1, the longer the beacon reception time (i.e. the period “F”) is, the more the power consumption is. In addition, refer to FIG. 2, which is a schematic diagram of a beacon service period F according to the prior art. In general, right after the TBTT timer expires, the beacon is transmitted from the AP. However, if the channel is busy, the beacon transmission will be delayed. Thus, the Wi-Fi station has to stay awake longer for receiving the beacon and therefore consumes more power. Moreover, if a length of the beacon is longer, the Wi-Fi station will spend more time on receiving the entire beacon, which also costs more power.
Accordingly, how to improve the power consumption in power saving mode is a very important target for battery life extension.